Magnetic core readout



p 1957 J. c. MALLINSON ETAL 3,344,413

MAGNETIC CORE READOUT Filed Jan. 4, 1963 2 Sheets-Sheet 1 Twp.

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p 1967 J. c. MALLINSON ETAL 3,344,413

MAGNETIC CORE READOUT Filed Jan. 4, 1963 2 Sheets-Sheet z I N VEN TORS 069W 6? Mam 5am fffRNE Y5.

United States Patent O 3,344,413 MAGNETIC CURE READOUT John C. Mallinson, Palo Alto, Calif., and Lawrence G. Wiley, Camp Hill, Pa, assignors to AMP Incorporated, Harrisburg, Pa.

Filed Jan. 4, 1963, Ser. No. 249,465 Claims. (Cl. 340-174) This invention relates to a magnetic core system, and more particularly to an improved way of reading out information from magnetic cores.

An object of this invention is to provide a drive arrangement which can deliver directly from a magnetic core circuit a considerable amount of power to one or more readout devices.

Another object is to provide a readout system of this kind which is simple, reliable, and inexpensive.

A further object is to provide for the non-destructive, interference-free readout of information at a sizable power level from minor apertures of multi-aperture magnetic cores.

A more specific object is to provide a practical arrangement for the visual display of the information stored in a magnetic core circuit.

These and other objects will in part be understood from and in part pointed out in the following description.

In US. Patent 2,995,731, there is disclosed a shift register comprising a number of multi-aperture magnetic cores (MADs) and connecting wire only. The cores are divided into even and odd groups and connected in sequence, a core of one group being able to transmit a binary one or zero to the next core in the other group, and so on. To shift the binary information, which is stored in the form of magnetic flux, in one core to the next, the groups of cores are energized by drive currents applied in proper sequence to an advance odd to even (ADV O to E) winding, an advance even to odd (ADV E to O) Winding, and a prime winding.

It is advantageous because of cost, size and circuit efiiciency to use rather small MAD cores in a shift register such as described above. Typically these cores are about the size of a shirt button. Now, because of the small size of the cores, their power handling capacity is quite limited. Generally speaking, with cores of this small size it is impossible to light a small incandescent light bulb directly from a core using previously known readout techniques. This is made even more difficult where a number of bulbs are used, as for example in a multicore shift register. Here some, none or all of the bulbs may be lighted depending upon the respective information status of the cores in the register. Thus, a widely varying load is placed on the power supply for the bulbs. Previously, even though a given supply circuit had been able to light one or a few bulbs, there was undesirable variation in brightness of the bulbs as more and more were turned on or olf. Thus as a practical matter, such a visual display arrangement has not heretofore been satisfactory.

In accordance with the present invention in one specific embodiment thereof, each odd core of a multi-core MAD shift register is provided with a respective incandescent light bulb which is turned on or ofi in accordance with whether the core is set with a one or a zero. Each bulb, when on, glows with a constant brightness regardless of how many or how few bulbs are lighted at a particular instant. A unique power supply or drive circuit for the bulbs provides continuous, non-destructive readout from a minor aperture of each core, and this is achieved without interfering with normal operation of the shift register. The power supply is designed to provide essentially constant current to a drive winding linking all of the minor readout apertures of the cores, the frequency, amplitude and waveform of this current being particularly chosen so that in relation to the size and material of the cores they are most efficient in driving the respective light bulbs coupled to them. An added advantage of the invention is that the normal operation of the circuit, as a shift register, is not affected.

A better understanding of the invention together with a fuller appreciation of its many advantages will best be gained from the following description given in connection with the accompanying drawings wherein:

FIGURE 1 is a schematic diagram of a MAD :core shift register wherein small incandescent bulbs are coupled respectively, to the odd-numbered cores to give continuous readout indications in accordance with the invention,

FIGURE 2 is a greatly enlarged detail of the light bulb drive and coupling windings at the readout aperture of a core, and

FIGURE 3 is a circuit diagram of the power supply or driver for the light bulbs provided according to the invention.

The magnetic core circuit 10 shown in FIGURE 1 includes a number of MAD cores 11 and 12 which are arranged respectively, in a group of odd-numbered (0) cores and a group of even-numbered (E) cores as indicated. There may, for example, be forty odd and forty even cores in the register, but for simplicity only two in each group are shown.

Information, either a binary one or a binary zero, is fed into the first 0 core of the register by means of an input winding 14 threading a minor input aperture 16 of the core. When the core is saturated with flux in the clockwise direction it is said to be set with a zero; when the core is saturated partly in the clockwise and partly in the counterclockwise direction, it is said to be set with a one. Thereafter, by application of suitable currents in the proper sequences to a prime winding 18 threading a minor output aperture 20 of the first odd core (as well as the others in this group), and to an advance 0 to E winding 22 threading the major apertures of the 0 cores, information stored in an odd core is transferred to the next E core. The minor output aperture 20 of each 0 core is threaded by a respective coupling winding 24 which also threads a minor input aperture 26 of the next E core 12. Information transferred to an E core is similarly shifted in turn to the next 0 core by currents applied to prime winding 18 linking a minor output aperture 28 of the E core, and to an advance E to O winding 30 through the major apertures of the E cores. Each E core is connected to the next 0 core by a respective coupling winding 32 threading aperture 28 and a minor input aperture 34 of the 0 core. A more detailed explanation of the operation of such a shift register will be found in the aforesaid U.S. patent.

Now, each 0 core 11 of circuit 10 is provided with a minor readout aperture 40, which, as seen also in enlarged detail in FIGURE 2, is threaded in figure-8 fashion by a drive winding 42 and by a load winding 44. The latter is connected to a respective one of the small incandescent light bulbs 46. There is applied continuously to drive winding 42 a steady, sinusoidal current from an RF drive unit 48. The current from the unit has a frequency sufiiciently high so that the magnetic material of the core, when it is in a locally switchable state about aperture 40, will just complete switching as the current through winding 42 begins to reverse. A suitable frequency is, for example, 300 kilocycles. This gives higher efficiency in driving the light bulbs than would an appreciably lower frequency. It is also desirable to use a sine waveform, rather than a square wave, for example, since flux switching about aperture 40 will take place smoothly over each cycle.

When an core is set with a binary one, there will be, for reasons known to the art, a flux locally switchable around a minor aperture of the core. In this event, the high frequency current flowing in drive winding 42 causes switching of flux locally around minor aperture 40, but not around the major aperture, nor around any other minor aperture of the core. This local switching of flux will induce a current in load winding 44 causing bulb 46 to glow with a desired brightness. When an 0 core is set with a zero, its respective bulb 46 will not be turned on because no flux can be switched locally around aperture 40 and there is no magnetic coupling between windings 42 and 44.

The brightness of each bulb when on, is essentially independent of how many or how few bulbs are lighted at a given instant. This is accomplished by maintaining the current in drive winding 42 effectively constant regardless of the size of the load coupled to the winding. In the case of a forty bulb register, this load can vary by over fiveto-one. To accommodate this variation, RF drive 48 is made to operate as a constant current source.

The operation of the shift register, as a shift register, is not affected by drive winding 42 and the light bulbs coupled to the 0 cores. Thus, during normal shift register operation, drive unit 48 can be left on. Stated differently, continuous readout from the 0 cores, without adverse interaction of the RF drive and load upon the shifting of information from one core to the next, is obtained.

The drive and load winding configuration shown in FIGURE 2 insures that both legs of a core 11 at its minor aperture 40 will be properly driven by current in winding 42. It is possible in the present circuit to use a different arrangement, for example, a single turn of wire through aperture 40 for winding 42 and a single turn for winding 44. However, in this case the circuit will be unuseable for commercial purposes and there will be a substantial adverse elfect on the operation of the circuit as a shift register. For the particular winding arrangement shown in FIGURE 2, drive current on winding 42 is about half enough to switch flux around the major aper ture of a core. With a core made of General Ceramics type 5209 ferrite material, having a thickness of 0.060 inch, a major aperture diameter of 0.240 inch and an outside diameter of 0.36 inch, 400 ma. peak to peak of sine wave current at 300 kc. on winding 42 is suitable for lighting up to forty G.E. type 331 bulbs connected, respectively, across windings 44. A bulb of this type is rated at 1.35 volts and 60 ma.

FIGURE 3 shows details of a circuit especially suitable as RF drive 48. Here, a first transistor 50 is connected as a Colpitts oscillator. The frequency of the oscillator is determined by the inductance presented by a primary winding 52 of a transformer 54, this winding being in parallel with a capacitor 56 in series with a capacitor 58. Positive feedback of voltage to transistor 50 is by means of a resistor 60.

Coupled to transformer 54 by means of a secondary winding 62 is a second transistor 64 which operates as a Class A amplifier. The collector of the latter is connected to the primary of an output transformer 66, the secondary of which is connected to winding 42: The voltage output from transformer 66 varies with the load presented by winding 42, the current to this winding remaining substantially constant. For the sake of completeness, actual circuit values are shown in FIGURE 3. Additional details of operation of the circuit will be understood by those skilled in the art.

The above description is intended in illustration and not in limitation of the invention. Various changes or modifications in the embodiment set forth may occur to those skilled in the art and may be made without departing from the spirit or scope of the invention as set forth. In particular, instead of a light bulb, a sensitive D.C. relay may be operated directly from a winding 44 by connecting it to the winding via a rectifier.

We claim:

1. An improved magnetic core shift register arrange ment with visual indication of the position of the ones and zeroes, said arrangement comprising a plurality of MAD cores, means connecting said cores in a shifting sequence, means to shift binary information from one core to the next, at least certain of said cores having minor readout apertures, a respective load winding coupling each readout aperture, a respective display device connected to each load winding, drive means threading each readout aperture, and a constant current driver for applying to said drive winding means a varying electric signal to give a substantially constant magnetomotive switching force around each readout aperture regardless of the number of said display devices being driven.

2. The arrangement in claim 1 wherein said devices are incandescent bulbs, and said electric signal is a constant amplitude sine wave current.

3. An improved readout system for multi-aperture magnetic cores, comprising a plurality of rnulti-aperture magnetic cores, each core having a minor readout aperture and a major aperture, means to set a binary one or a zero into said cores, a plurality of loads coupled respectively to each said readout aperture, a drive winding threading said readout apertures, and a high frequency drive unit to apply current to said drive winding, the current applied by said drive unit being substantially constant.

4. The system in claim 3 wherein said cores are of material substantially like General Ceramics type 5209 ferrite, the frequency of said current being approximately 300 kc., and the variation in impedance of said loads being over ten-to-one.

5. An improved magnetic core arrangement with readout provision for the respective binary ones and zeros in the cores, said arrangement comprising a plurality of multi-aperture magnetic cores, each of which has at least a major aperture and a minor readout aperture, means to shift a binary one and a binary zero into each of said cores, a plurality of loads each of which is coupled to a respective one of said readout apertures, and drive means including a winding threading said readout apertures, said drive means applying a varying electric signal to said readout winding to give a substantially constant magnetomotive switching force around each readout aperture regardless of the information states of said cores, whereby each load will be driven or not on a continuous basis by said drive means depending on wehther a binary one or a zero is set into the respective core, the information state of each core can be changed without disconnecting the load or deenergizing said drive means, and the drive to each load will be substantially constant regardless of the number of loads being driven.

References Cited UNITED STATES PATENTS 2,851,677 9/1958 Crooks 340174 3,156,905 11/1964 Stram 340174 3,173,133 3/1965 Jakubas 340174 3,174,139 3/1965 Vecchiarelli 340174 3,214,600 10/1965 Schreiber 340174 3,231,873 1/1966 Sweeney 340174 BERNARD KONICK, Primary Examiner.

M. S. GITIES, Assistant Examiner. 

5. AN IMPROVED MAGNETIC CORE ARRANGEMENT WITH READOUT PROVISION FOR THE RESPECTIVE BINARY ONES AND ZEROS IN THE CORES, SAID ARRANGEMENT COMPRISING A PLURALITY OF MULTI-APERTURE MAGNETIC CORES, EACH OF WHICH HAS AT LEAST A MAJOR APERTURE AND A MINOR READOUT APERTURE, MEANS TO SHIFT A BINARY ONE AND A BINARY ZERO INTO EACH OF SAID F CORES, A PLURALITY OF LOADS EACH OF WHICH IS COUPLED TO A RESPECTIVE ONE OF SAID READOUT APERTURES, AND DRIVE MEANS INCLUDING A WINDING THREADING SAID READOUT APERTURES, SAID DRIVE MEANS APPLYING A VARYING ELECTRIC SIGNAL TO SAID READOUT WINDING TO GIVE A SUBSTANTIALLY CONSTANT MAGNETOMOTIVE SWITCHING FORCE AROUND EACH READOUT APERTURE REGARDLESS OF THE INFORMATION STATES OF SAID CORES, WHEREBY EACH LOAD WILL BE DRIVEN OR NOT ON A CONTINUOUS BASIS BY SAID DRIVE MEANS DEPENDING ON WHETHER A BINARY ONE OR A ZERO IS SET INTO THE RESPECTIVE CORE, THE INFORMATION STATE OF EACH CORE CAN BE CHANGED WITHOUT DISCONNECTING THE LOAD OR DEENERGIZING SAID DRIVE MEANS, AND THE DRIVE TO EACH LOAD WILL BE SUBSTANTIALLY CONSTANT REGARDLESS OF THE NUMBER OF LOADS BEING DRIVEN. 